Each title will be sold for 10% off until March 24. An Unreal Deal Pack is also available, containing the five titles for $59.95--a savings of over $46. The discount applies to the Unreal Deal pack as well, making it $53.95 until March 24.

"Epic is a leading developer of game engine technology and has produced some of my favorite games of all time," said Valve president Gabe Newell. "It's an honor to be working with them and offering their current and classic titles to the millions of Steam gamers around the world."